It doesn't have one natively. There are no Digital connection that'll work from the word go. He wouldn't even find anywhere to plug in a toslink.
You need to buy a convertor called the Creative I/O from Creative, that converts the A to D 3.55mm jack to a digital connection, which is the 3.55mm jack on the right of the sound card, which includes SPDIF in/outs, for Optical and Coaxial.
I have it for my Xtreme Music and it works a treat
Shame they are so hard to find.
Its out of stock on the main site at the moment for the US